Over the past decades, communities all over the world have made concerted efforts to reduce the risk of global warming. Unfortunately, there is no single unique solution to the problem. Thus, during the coming decades energy efficiency will be a critical factor in reducing carbon emissions and fighting global warming. The power generation industry and transmission and distribution industries (T&D) contribute to a large part of energy losses in the society. The losses in T&D systems alone are total 10% of a global average of the T&D energy transferred.
There is thus a need for investments in efficient use of energy, in the energy efficiency of electric power infrastructures and in renewable resources. Development of an efficient system for using electricity may enable larger scale use of primary energy in the form of electricity compared to the situation today.
Contributing to at least one-third of total T&D losses, transformers and shunt reactors are commonly the most expensive components in the power system and hence efficient design of these power devices could reduce the T&D losses.
Moreover, the European Commission (EC) has set a series of goals demanding climate and energy targets to be met by 2020, known as the “20-20-20” targets. In line with the “20/20/20” targets the European Commission (EC) and organizations making transformer standards are currently working on developing directives to reduce transformer losses.
One way to reduce losses in transformers are not only to buy transformers with minimum losses as defined in standards e.g. EN 50464-1 but also to apply loss evaluation values in the procurement process.
Available scientific methods to reduce transformer losses below the present level, are scanty. However, one method for distribution transformers is to use amorphous steel in as the core material. With this amorphous technology may be possible to reduce the no load losses up to 70%. Also by decreasing the current density and/or flux density below the limit needed for a reliable transformer, a wide range of transformer designs with lower losses can be achieved with more material.
U.S. Pat. No. 4,668,931 discloses a transformer core having one or more winding legs built up from a plurality of silicon steel laminations and a pair of yokes built up from a plurality of amorphous steel laminations. The yokes and legs are serially joined by silicon steel-amorphous steel lamination joints to create a magnetic loop circuit and thus provide a transformer core having significantly improved core loss characteristics as compared to a power transformer core formed exclusively of silicon steel laminations.
However, there is still a need for an improved transformer design.